Regarding conventional battery cooling structures, for example, Japanese Patent Laying-open No. 2004-1683 (Patent Document 1) discloses a vehicular battery cooling structure to prevent deterioration of battery characteristics and short life thereof. The vehicular battery cooling structure disclosed in Patent Document 1 includes an air intake duct connected to a battery pack, and an air sending fan distributing cooling air to the air intake duct in order to cool the battery pack. The air intake duct is provided with an air inlet located above a tonneau cover for covering a luggage placed in a luggage room.
Further, Japanese Patent Laying-open No. 5-169981 (Patent Document 2) discloses a device, provided in an electric car, for cooling a battery mounted therein by means of external air drawn in from a front end portion of the car body. In Patent Document 2, the electric car is provided with a hollow side frame extending from the front end portion to the rear end portion of the car body. The side frame has a front end portion in which an opening is provided to draw in the external air therethrough, and the external air thus drawn in passes through a battery storage room and thereafter is exhausted from an opening provided in the rear end portion of the side frame.
Further, Japanese Patent Laying-open No. 2006-182044 (Patent Document 3) discloses a high voltage battery unit mounting vehicular structure by which a high voltage battery having a particularly large capacitance can be mounted on a vehicle. In Patent Document 3, the high voltage battery is disposed on a rear floor panel of the rear portion of a fuel battery vehicle.
Furthermore, Japanese Patent Laying-open No. 2002-231321 (Patent Document 4) discloses a vehicular battery cooling device achieving improved cooling efficiency without complicating the structure of an air outlet of an air exhaust duct. In Patent Document 4, the air outlet of the air exhaust duct is provided between a deck side trim and an outer body to exhaust the air after cooling the battery.
In Patent Document 1 described above, air in the vehicular cabin is introduced into the luggage room as cooling air to cool the battery pack generating heat due to charging and discharging. In this case, continuous airflow from the vehicular cabin to the luggage room causes internal pressure drop in the vehicular cabin, whereby the air in the luggage room may be brought back to the vehicular cabin. The air in the luggage room has a high temperature due to influences of the battery pack generating heat and the cooling air exhausted from the battery pack. When such high temperature air is brought back to the vehicular cabin, an occupant in the vehicular cabin may feel unpleasant about the flow of such air, or the high temperature air may be drawn into the luggage room again to decrease the cooling efficiency of the battery pack.